(1) Field of the Invention
The present invention relates to an oil base ink composition which is suitably used for recording inks such as a stamp ink and an ink jet ink and inks for writing tools such as an ink for a ball point pen and an ink for a marking pen.
(2) Description of the Prior Art
Inks for writing tools and recording inks have so far been divided roughly into water base inks and oil base inks.
In the case of, for example, an ink used for a stamp pad, a water base ink penetrates primarily through a paper surface and is dried and fixed thereon. Accordingly, the ink has a low penetrating rate and a very inferior drying property to hard-absorbing faces of art paper and coated paper. Further, in the case where a water base ink sticks on a rubber seal face in a large amount, because of the poor wettability of the ink on a rubber seal face, the drying property is inferior, and the print seal tends to be blurred. In contrast with this, if the amount of the ink adhered on a rubber seal face is controlled to a small amount, the adhesion thereof becomes thin, and the print seal in stamping becomes stained. Further, since a water base ink uses a water soluble dye, it has the defect that it has a poor water resistance.
On the other hand, oil base inks for a stamp include two kinds of a type using a scarcely volatile solvent and a type using a highly volatile solvent, and both have a very good water resistance. However, while the former type has the advantage that because of a scarce volatility thereof, the stamp pad does not have to remain always in a closed state, it has the defect that the print seal put on non-absorbing faces of art paper and coated paper has a low drying property since the ink is adhered on a paper surface primarily by penetrating-drying as is the case with a water base ink. On the other hand, the latter type has the advantage that the print seal put on a non-absorbing face has a high drying property since the ink is adhered on a paper surface primarily by evaporating-drying. However, since the ink contains the highly volatile solvent, the amount of the ink adhered on a rubber seal face is obliged to be increased in order to prevent drying, and as a result thereof, excess adhered amount of the ink causes the print seal to lack in sharpness. In addition thereto, it has the defect that because of a high volatility of the ink, leaving the cover of the stamp ink pad in an open state for a while makes the surface thereof dry to extremely lower the adhered amount of the ink, which results in the blurred print seal or impossibility of sealing.
In the case of an ink for a marking pen, an oil base ink is used as an ink capable of writing on both absorbing faces of paper and cloth and non-absorbing faces of plastic, glass and metal. On the other hand, however, it has the problems that leaving the pen with a cap taken off causes the ink to be dried and solidified to precipitate the ink component at the pen tip and lower the ink feeding amount and therefore prevents the ink from flowing out of the pen tip, which result in blurring the drawn lines or causing impossibility of writing due to dry-up at the pen tip.
Other inks for ball point pens and inks for ink jet have the same problems.